1.1 This test method provides an indirect measurement of the viscosity of clay slurries using a funnel (Marsh Funnel) and a graduated cup of specific dimensions. This test method provides a practical indicator of the viscosity on a routine basis. This test method has been modified from the API Recommended Practice 13B-2.

1.2 The result determined using the method is referred to as the Marsh Funnel Viscosity.

1.3 This test can be performed in the laboratory, or used in the field to assess the apparent viscosity of a clay slurry for quality control purposes. The most commonly used slurry is a bentonite clay slurry.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.